Effect of Seashell and Eggshell Nanoparticles on Tooth Color Changes after Bleaching Using CIE L*C*H Color Space

Demineralization of dental structures is one of the post-bleaching effects. Remineralizing agents are recommended to overcome this problem. Synthesis of biomaterials from natural sources rich in calcium remains a viable and more economical option. Post-remineralization discoloration caused by such materials could disappoint patients who prefer whiter teeth; therefore, the color changes caused by such materials should be a concern during selection of the remineralizing protocol after bleaching.

This study aimed to evaluate the effect of seashell and eggshell nanoparticles on tooth color changes after bleaching using CIE L*C*H color space.

Forty natural maxillary incisors were enrolled in this study. Teeth were divided into four groups according to the applied treatment, G1: seashells paste for 2 minutes, G2: eggshells paste for 2 minutes, G3: 2% NaF gel for 1minute, and G4: received no treatment (control), then all specimens were stored in artificial saliva for 24hrs. The color of the specimens was determined according to the CIE L*C*H color space using a spectrophotometer at baseline, after bleaching, and after remineralization. Colors were compared using the ΔL*, ΔC*, and ΔH* parameters as well as the total color difference (ΔE) after bleaching and remineralization.

After bleaching; there was a statistically significant difference between the experimental groups for ∆C, ∆H, and ∆E. After remineralization, there was a statistically significant difference in the mean values of ΔL, ΔC, ΔH, and ΔE between groups, the lowest mean value of (ΔE) recorded with eggshells, followed by 2% NaF gel, then seashells, while the highest mean value of ΔE was recorded with the control group.

After bleaching, nano-eggshells and 2% NaF maintained the post-bleaching color, indicating the recovery of the damaged enamel surface. Enamel treatment using seashells could negatively affect the effectiveness of whitening.